1. Field of the Invention
The present invention relates to a diving watch, particularly to watch capable of measurement and recording of diving data such as time, depth, and water temperature, and more particularly to a dive computer capable of making a graphical display of safety stop information or decompression stop information.
2. Background Art
Over the past 20 years of widespread growth of diving, technological development has progressed in the area of scuba diving and skin diving watches (diver's watches) capable of measuring and visually displaying depth, diving time, and water temperature and the like during a dive. In addition, starting about 10 years ago there has been rapid growth in dive computers which continuously monitor the body's nitrogen level which is become problem in scuba diving and calculate and display important data such as how much remaining time a diver has for a dive. An example of a dive computer, as in, for example, Japanese unexamined patent publication (KOKAI) No. H5-141973, enables determination of the proportion with respect to the safe allowable limit amount of inert gases in body tissues when resurfacing, following the algorithm shown in FIG. 9, which illustrates the case of Japanese unexamined patent publication (KOKAI) No. H5-141973 described below.
When a dive is begun (step S4), the water pressure is detected and the water depth is calculated (steps S6 and S7), the nitrogen partial pressure in the body being calculated based on the calculated water depth (step S8). The ratio of this internal body nitrogen partial pressure to a limitation of the safe allowable amount of internal body nitrogen partial pressure stored in ROM is calculated (step S9) and, if the internal body nitrogen partial pressure is less than the safe allowable limit amount, the amount of no-decompression diving time is calculated (steps S10 and S11), and the ratio of the internal body nitrogen partial pressure to the safe allowable limit amount is displayed along with the water depth and the like (step S12). At step S10, if the internal body nitrogen partial pressure exceeds the safe allowable limit value, the decompression stop water depth and decompression stop time are calculated and displayed, together with the ratio of the internal body nitrogen partial pressure to the safe allowable limit amount thereof (steps S13 to S15).
In the water, although a diver determines the water depth for diving in accordance with the value calculated by a dive computer such as in the Japanese unexamined patent publication (KOKAI) No. H5-141973, because nitrogen is accumulated in the body within the computer indicated range, in order to release this nitrogen it is recommended that when surfacing a safety stop be made at a given depth for a given amount of time. When transitioning to decompression diving during a dive, it is necessary to release the nitrogen by stopping for a given time at a given depth indicated by the computer. In the past, when it is necessary in this manner to stop in the water for a given amount of time at a given water depth, this was done by looking at the digital depth display of the computer.
With the present invention, the depth displays for both safety stops and depth for decompression stops are not only displayed digitally but also indicated graphically, thereby making it easier to prompt the diver to maintain the depth.
The present invention provides a safe diving watch that provides a simple prompt to the diver to maintain the depth.